Bag-making machine



United States Patent Inventor Appl. No.

Filed Patented Assignee Priority Willi Stork Tecklenburg, Westphalia, Germany 684,327

Nov. 20, 1967 Aug. 18, 1970 Windmoller & I-lolscher Lengerich, Westphalia, Germany Nov. 28, 1966 Germany No. W42871 BAG-MAKING MACHINE 9 Claims, 10 Drawing Figs.

Int. Cl

83th 1/00 Field of Search 209/lil.5,lil.7,80

[56] References Cited UNITED STATES PATENTS 2,270,565 1/1942 Sharkey 209/80 3,278,747 l0/l966 Ohmart 209/] l l.5X 3,374,7 l 4 3/ l 968 Berghgracht 93/8 3,390,769 7/1968 Tatham et al 209/l ll 3,433,135 3/1969 Lokey et al. 93/8 Primary Examiner- Bernard Stickney Atmrney- Fleit, Gipple and Jacobson ABSTRACT: A bag-making machine comprises a deflector. which is disposed between the end closure-laying and delivery stations and is controlled by end closure-checking devices to reject defective bags from the path of conveyance. The end closure-checking devices comprise means for checking crossed end closures as to the presence of the inclined edges of the iniolded corner portions and the agreement of the actual position of such edges with their desired position.

Patented Aug. 18," 1970 Sheet br 3 INVENTOR Willi STORK By MQu-QM/M /ML hisATTOR NEYS Patented Aug. 18, 1970 Sheet of s mm m E V. N I.WB NQE w o 0 6 q mm 5, 0.2 wt st ob P a Q5 his ATTORNEYS Patented Aug. 18, 1970 3,524,389

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221 INVENTOR w1111 STORK his ATTORNEYS BAG-MAKING MACHINE It has already been proposed to provide a bag-making machine with a deflector, which is disposed between the end closure-laying and delivery stations and which is controlled by end closure-checking devices to reject defective bags from the path of conveyance. According to that prior proposal, the end closure-checking devices comprise suitably individual sensing elements for the inner and outer edges of each end closure and another sensing element for each end patch. An error signal from each sensing element causes a deflection of the deflecfor.

That prior proposal is covered by the pending U.S. Patent Application Serial No. 484,387 filed September 1, 1965.

The present invention relates to a further development of the subject matter of that prior proposal and has as its object not only to check the size and location of the bag end closures and the presence and the correct location of the end patches but to detect other defects which may occur in production and to eliminate the workpieces having such defects.

in the manufacture of bags which have two crossed end closures in transversely conveying bag-making machines, one end of the tube section may not be pulled open to form an open crossed end closure whereas in the succeeding station serving to reversely fold the lateral end flaps the tube section end which has not been pulled open is reversely folded and then provided with an end patch. The end closure-checking devices provided according to the above-mentioned prior proposal will not detect the defect of such workpiece end closure so that such bag will not be rejected although it cannot be used. A tube section end which has not been pulled open but has been reversely folded in the width of the lateral end flaps differs from a perfect end, inter alia, in that the corners of the bag are not at an angle of 45 as a result of the fact that the corner portions are normally infolded when the end is being pulled open, but said corners are at right angles.

In the station for laying the open crossed end closures, another defect in the manufacture of bags having crossed end closures may occur because an infolded corner portion assumes a screw orientation. If this skewing takes place toward the end of the tube section, a portion of the tube will protrude from the normal bag end closure so that there is bag material at a point where no such material is permissible, just as with a tube section end which has not been pulled open at all and has been folded back in accordance with a lateral end flap. The same defect may occur at the inner inclined end edges which lie on the body of the bag; in this case there is additional bag material at a point where only the two plies of the bag workpiece are desired.

The edges of the workpiece may also be defective in that they do not lie outside the proper contour of the bag but are inwardly displaced relative to that contour. These defective bags have been provided with a reduced external contour at some point as a result of an improper folding operation. In the cases discussed hereinbefore, it has been assumed that an improperly infolded corner portion always results in a bag edge which protrudes toward one side or the other (inwardly or outwardly) over the normal, protruding bag edge adjacent to the inclined end edges. Alternatively, only one inclined end closure edge of a bag may have been rearwardly displaced by upsetting.

ln bag-making machines, a tube section end may not be pulled open to form an open end closure because the tube section opening is closed by adhesive which has been improperly applied adjacent to the cut and squeezed out but the spreading tools reversely fold the tube section end portion inwardly onto the body ofthe bag about the prescored center fold line ofthe end closure. In this case, the end of the reversely folded portion lying on the body of the bag is folded back in the station for reversely folding the lateral end flaps and an end patch is subsequently adhered over said portion. Bearing in mind that the extreme end portion of the tube section is reversely folded twice and is prescored at the leading corner for the formation of the infolded corner portion, said leading corner may run against a tool and be folded back before the end patch is adhered. This will result in a bag in which an additional, third ply is folded on top.

Another defect of the bag workpieces may reside in that the four outer main boundary edges of the bags are displaced to form a parallelogram as a result of an inclination of the tube sections. Whereas the end closures of such bag have edges in the desired position so that they are not recognized as rejects by the elements which check the width of the end closures, the forward and rear edges of such bags are inclined rather than at right angles to the end closure edges. As a result, the inclined edges of at least one end closure are not in their desired position. Such a bag is a reject because there is a partial lack of material at the lateral end flaps owing to the inclination and the adhered lap joint of the lateral end flaps is improper in part.

It is an object of the present invention to prevent in a bagmaking machine according to the above-mentioned prior proposal a delivery or further conveyance of bags having the defects described hereinbefore together with the satisfactory bags.

This object is accomplished according to the invention in that the end closure-checking devices comprise means for checking crossed end closures as to the presence of the inclined edges of the infolded corner portions and the agreement of the actual position of such edges with their desired position.

When it is only desired to distinguish satisfactory end closures from bags in which the tube section end has not been pulled open but has been reversely folded in accordance with the width of the lateral end flaps, and to eliminate such defective bag workpieces, in which the corners are at right angles rather than inclined at 45 by the normal formation of infolded corner portions when the tube section end is being pulled open, it will be sufficient to provide at least one sensing element in the path of travel of the outer end closure halves and to feed the deflector control circuit only with the error pulses which are generated during a short time immediately before the desired entry time of the leading inclined edges of the infolded corner portions into the sensing area. The sensing action is preferably restricted in the direction of travel to an intermediate portion of the sensing range so that a response to position errors of the bag workpieces in the direction of travel will be avoided.

If bag workpieces having skewed infolded corner portions are also to be detected, another sensing element for each of the trailing inclined edges may be provided according to the invention in the path of travel of the outer end closure halves and may be spaced from the sensing element for the leading inclined edges by a distance which exceeds the length of the fold lines defining the lateral flaps and which is smaller than the length of the center line of the end closure, the deflector control circuit being fed only with the error pulses which are generated during a short time immediately after the desired exit time of the trailing inclined edges of the infolded corner portions from the sensing range of these sensing elements.

To enable also a detection of inclined edges which belong to infolded corner portions and which are set back from the proper contour of the bag, and a rejection of bags having this defect, further sensing elements for the leading and trailing inclined edges may be provided in the path of travel of the outer end closure halves, the deflector control circuit being fed only with the error pulses which are generated during a short period of time immediately after the desired exit time of the leading inclinededges of the infolded corner portions and immediately before the desired entry time of the trailing inclined edges of the infolded corner portions from the respective sensing range.

Sensing elements corresponding in arrangement and function to the sensing elements disposed in the path of travel of the outer end closure halves and described hereinbefore may be arranged according to the invention in the path of travel of the inner end closure halves to enable a detection of skewed infolded corner portions in this part of the tube section too. lt will be sufficient in general, however, to provide in the path of travel of the inner end closure halves only sensing elements which detect an outward deviation of the inclined end closure edges from the desired contour because an upsetting resulting in inward deviations from the proper contour of the bag need not be expected adjacent to the inner end closure halves.

The previously described sensing elements may also be used to detect the above-mentioned parallelogramlike displacements of the four outer main boundary edges of the bags due to an inclination of the tube sections. In this case too there is bag material at points where there is no bag material in a bag having the proper contour so that, e.g., one of the sensing elements for the leading inclined end closure edges will respond.

With respect to the last-mentioned defects in bags it may be suitable to provide not only the sensing elements for the leading inclined closure end edges as well as further sensing elements in the path of travel of the outer ends of the leading edges of the bag. When the tube section ends have not been pulled open at all, it will be sufficient if the sensing element becomes effective somewhere adjacent to the protruding, right-angled bag corner. If the infolded corner portions are skewed, relatively large tolerances are also permissible because the bags are still useful with smaller deviations. On the other hand, the permissible tolerances are much smaller if the workpieces moving through the machine have been deformed to the configuration of a parallelogram because even slight deviations from the rectangular configuration will result in improper adhered lap joints at the lateral end flaps and such joints will adversely affect the usefulness of the bag. The use of the additional sensing elements for sensing the outer ends of the leading edge of the bag enables the main- 1 tenance of a tolerance range which differs from the tolerance range maintained by the sensing elements in the path of travel of the outer end closure halves. The sensing elements may be so arranged that bags having infolded corner portions which are skewed within the tolerance limit will not be rejected whereas inclined bags will be detected and rejected if they exceed a much smaller tolerance range.

The blanking during the times when the sensing elements should be ineffective in accordance with the invention rather than connected to the deflector control circuit may be effected in dependence on the machine cycle by means of switches which are operated by a timing disc, which rotates in synchronism with the operation of the machine and may consist, e.g., of a camwheel performing one revolution during the passage of each bag workpiece. Practical experiments have shown that the movement of the bag workpieces through the machine is often timed with insufficient accuracy so that the arrival of the bag edges to be sensed does not agree with the performance of a revolution of a timing disc so closelyas to enable a detection of slight deviations such as occur with skewed infolded corner portions or with the bag workpieces which have been deformed into a parallelogram. To control the active times of the sensing elements with the accuracy which is required for the detection even of minute deviations at the workpiece, the sensing elements may be connected to the deflector control circuit by switches and sensing elements which are operated by the leading or trailing edges upon the arrival thereof. The switches which are controlled by the elements for sensing the leading and trailing edges are then connected in series with the switches which are controlled by the elements for sensing the inclined edges of the bag or the ends of the leading edge. In this case, the sensing elements are disposed substantially in accordance with the contour line of the bag so that they are approximately simultaneously acted upon by the edges of a properly folded bag. The elements for sensing the leading and trailing edges of the bag are suitably disposed behind and before the bag edge, respectively, in the direction of travel with respect to the bag body so that the switch controlled by them is already or still open when the elements for sensing the bag corners leave or enter the error range. This offset may be varied to set the tolerance range for properly folded bags. if the sensing elements for the detection of defects are controlled by sensing elements acted upon by the bag edges and it is assumed that a given portion of the bag is always in its desired position, the remaining bag portions will be checked as to their agreement with the desired contour. The sensing elements for detecting errors will be disconnected by the sensing elements which respond to the reference edge after or before the bag workpiece has moved or is moving through the error range of the respective sensing element.

For those sensing elements which serve to detect bags having an outer contour which is reduced in size owing to an improper folding, the relations are inverted also as regards the elements for sensing the reference edge so that the reference edge-sensing elements cooperating with said error-sensing elements are suitably disposed before and behind the bag edge, respectively, in the direction of travel with respect to the bag body so that the switch controlled by them is already or still closed when the error range of the bag workpiece enters the sensing range.

The sensing elements may be suitably adjustable in the direction of conveyance of the machine.

Within the scope of the invention, mechanical feelers may be used as sensing elements. Such mechanical feelers are actuated by the arriving bag edge and are arranged either to close a contact or to open a previously closed contact. The feelers disposed at the inclined edges of the bag and at the ends of the leading edge of the bag close a contact while they are acted upon by the bag workpiece. These feelers are connected in known manner to a feeler which senses the intermediate portion of the leading or trailing edge of the bag and controls a contact which is open during the action of the bag workpiece on the latter feeler. The arrangement of the sensing elements will then determine the tolerance range. A high accuracy will be obtained because the feeler which responds to the leading or trailing edge of the bag eliminates the dependence on an accurate timing of the workpieces, as would be the case with a timing disc.

Within the scope of the invention, photoelectric sensing elements, preferably photodetectors for receiving reflected light, may be alternatively used, particularly in the path of the outer end closure halves, the ends of the leading edge of the bag, and the reference edges. The sensing elements in the path of the inner end closure halves may also consist of photodetectors for receiving reflected light and of stationary reflectors, which cooperate with said photodetectors and enter between the top wall of the bag and the end closure of the bag because the error ranges of the inclined edges of the inner end closure halves may also be photoelectrically sensed in this manner.

On the other hand, a source of radioactive radiation, preferably beta radiation, may be disposed in the sensing range, and a receiver, preferably a scintillation counter, may be disposed beyond the plane of travel of the workpieces and cooperate with a switch. Such arrangements for counting the number of plies of the bag workpieces may be used particularly for scan the error ranges of the inclined edges of the inner end closure halves or generally to indicate whether the number of plies differs from the normal number of plies at a certain point or in a certain area. Such sensing elements may be used to special advantage instead of the mechanical sensing elements used according to the above-mentioned prior proposal for sensing the inner edges of the crossed end closures. Different sensing elements may be used within the scope of the invention for detecting and rejecting bag workpieces which result when the spreading tools reversely fold the tube section end inwardly about the prescored center fold line of the end closure, as has been described hereinbefore, the end portion of the reversely folded part which lies on the bag body is then backfolded in the station for reversely folding the lateral end flaps, and an end patch is subsequently adhered to said end portion. As has also been mentioned hereinbefore, the prescored leading corner of the twice reversely folded, extreme outer end portion of the tube section of such defective workpieces may be backfolded before the end patch is adhered thereto so that an additional, third ply of the bag is folded on top.

Based on the recognition that such workpiece has no sheet material other than the end patch adjacent to the outer lateral end flap, the invention proposes to check the correct position of the outer end closure halves by sensing elements consisting of pairs of sensing rollers, which are provided at both ends of a double-armed lever, which is pivoted against spring force about an axis which is disposed, e.g., over the path of travel of the center line of the end closure and parallel to the latter, said lever operating by means ofa switch the deflector control circuit when the lever is pivotally moved beyond a predeter mined angle. These sensing elements are suitably mounted to be bodily pivotally movable against spring force about axes which are transverse to the direction of travel.

The invention will be described more fully hereinafter with reference to the accompanying drawings, which show an illustrative embodiment.

FIG. I is a diagrammatic top plan view showing a checking and rejecting device embodying the invention and incorporated in a bag-making machine.

FIG. 2 is a circuit diagram of the checking and rejecting device shown in FIG. l.

FIG. 3 is a top plan view showing a bag workpiece which is defective because a tube section end has not been pulled open.

FIG. 4 is a top plan view showing a bag workpiece which is defective because it has an infolded corner portion which is skewed outwardly.

FIG. 5 is a top plan view showing a bag workpiece which has been improperly folded because it is inclined.

FIG. 6 is a diagrammatic top plan view showing a bag workpiece broken away with associated sensing elements for detecting defects outside and inside the desired contour of the bag.

FIG. 7 is a top plan view showing a bag which is defective because one tube section end has been reversely folded although it has not been opened.

FIG. 8 is a side elevation showing a sensing device for detecting defective bags according to FIG. 7.

FIG. 9 is a sectional view taken on line lX-IX in FIG. 7 and showing an associated sensing device according to FIG. 8.

FIG. I0 is a sectional view like that of FIG. 9 but shows a normal end closure and an associated sensing device.

The bag workpieces, one of which is shown and designated 5, are fed between lower rollers 6 and upper rollers, not shown, in the direction 8 through a checking device to a deflector 25 for rejecting defective bag workpieces. The checking device according to the above-mentioned prior proposal consists of an element 13 for sensing an inner edge I4 of an end closure 9, an element 15 for sensing an inner edge 16 of an end closure 10, an element 17 for sensing an outer edge 18 of the end closure 9, an element 19 for sensing an outer edge 20 of the end closure 10, an element 21 for sensing an end patch I] and an element 22 for sensing an end patch I2.

According to the invention, the checking device according to the above-mentioned prior proposal is further developed to enable a detection and rejection also of defective bag workpieces such as are shown in FIGS. 3, 4, 5, 6, and 7. FIG. 3 shows a bag workpiece which is satisfactory at one end closure 140 whereas another end closure 141 of the bag is defective because the tube section has not been pulled open at this end, where the contour of the proper end contour is indicated by dash-dot lines. In the station for reversely folding the lateral end flaps, a tube section end 142 was reversely folded onto itself about a fold line I43 for the outer lateral end flap and was subsequently provided with an end patch 144. The bag end closure 141 differs from the normal bag end closure in its outer contour by right-angled corner portions 145 and I46, which are absent in the normal end closure.

The bag shown in FIG. 4 has again a satisfactory end closure 147 and is defective at its other end closure 148 because a corner portion has been infolded with a skew. Because the infolded corner portion is skewed outwardly at its leading end 150, a triangle I51 protrudes beyond the desired contour, which is indicated by dash-dot lines. The direction of travel is indicated by the arrow 149.

Another configuration ofa defective bag is shown in FIG. 5 in solid lines whereas the contour of a proper bag is indicated in dash-dot lines. The defective bag has defective lateral end flaps 152-I55, which have an improper taper toward one side and hardly overlap adjacent to said sides I56 and 157 so that they are not properly adhesively joined. The resulting bag is deformed into a parallelogram and unusable. This deformation is due to the fact that the tube section has moved with an inclination through the bag-making machine, as is indicated in FIG. 5. Such bag has an important disadvantage residing in the inclination of the leading and trailing edges of the bag.

For a detection and rejection of bag workpieces having such defects, the invention provides further sensing elements 159 and adjacent to the leading corners of the bag between the center line 158 of the end closure and the outer edges I8 and 20 of the end closure. These sensing elements 159 and 160 consist of light barriers and detect bags as shown in FIG. 3, which have not been pulled open, as well as bags as shown in FIG. 4, which have a skewed infolded corner portion because the additional triangle 146 (FIG. 3) as well as the protruding triangle I51 (FIG. 4) are sensed by the sensing elements 159 and 160.

Inclined bag workpieces as shown in FIG. 5 would also cause the sensing element I59 to indicate an error because the leading corner I61 ofthe bag in FIG. 5 is advanced relative to the normal position of said bag corner. However, the inclination must be measured with a much smaller tolerance than skewed infolded corner portions because the inclination results in weak bag end closures whereas an improper infolding of a corner portion substantially affects only the appearance of the bag. For this reason, further sensing elements 162 and 163 for checking the inclination are provided at the ends ofthe leading edge of the bag.

Additional sensing elements, not shown, are arranged like the sensing elements 159 and 160 and serve for detecting skewed infolded corner portions at the trailing corners of the bag.

The additional sensing elements disclosed hereinbefore enable a detection only of outwardly skewed infolded corner portions. For a detection of infolded corner portions which are skewed toward the inner end closure halves, i.e.. those end closure halves which lie on the body of the bag, additional sensing elements 164 and 165 are disposed adjacent to the leading corners of the bag between the respective center line 158 of the end closures and the inner edges I4 and 16 of the end closures. Sensing elements which are not shown are similarly arranged adjacent to the trailing bag corners. The inclined inner end closure edges 166 and I67 to be sensed by the sensing elements 164 and 165 lie on the body ofthe bag so that a light barrier cannot be used.

According to the invention, a photodetector for receiving reflected light may be used in conjunction with a shoe having a reflecting surface and entering between the body of the bag and the inner half of the end closure, which inner half is disposed over said bag body. In this arrangement, which is not shown, the reflecting surface of the shoe lying over the bag body, and photodetectors for receiving reflected light, four of which may be provided and arranged adjacent to the inner inclined edges at the leading and trailing ends of each end closure, enable a detection of an inward skew of all four infolded corner portions and a rejection of bags having such defect.

Within the scope of the invention, this object may also be accomplished by a sensing element which emits nuclear radiation. Such elements are used according to FIG. I as elements I64 and 165 for sensing the leading inner inclined end closure edges. The nuclear radiation consists of beta radiation, which is emitted, e.g., by cobalt. Beta radiation may be used industrially because it does not require expensive safety precautions.

The radiation source is accommodated in at protecting body of grey cast iron, which has an exit opening. A notice that the direct path of rays should be avoided is sufficient to avoid radiation damage. 1f the radiation source is disposed on one side of the plane in which the workpiece is conveyed and a counter tube is disposed on the other side of said plane, the counter tube will respond to a different number of plies entering the path of rays. The ratio between the number of plies of the bag body alone and the number of plies of the bag body and the superimposed bag end closure is 1:2. This will be perfectly indicated by the counter tube so that the latter can deliver a pulse when the improperly enlarged end closure enters below the counter tube. This pulse is amplified and then used to close a switch.

With all sensing elements 159/160, 162/163 and 164/165 which have been mentioned before, it is essential that a rejection of the bag be initiated only by defective bag edges which protrude outwardly beyond the normal bag contour. This is ensured by another sensing element 168, which is disposed at a bag portion where the bag edge is in proper position in any case so that this bag edge portion can be used as a reference for the measurement. The sensing element 168 consists of a light barrier or of a photodetector for receiving reflected light and is disposed at the intermediate portion of the leading edge 169 of the bag. All sensing elements which have been mentioned are arranged relative to each other in the direction of travel of the bag substantially in accordance with the contour of the bag so that the additional sensing element 168 senses the leading edge 169 of each arriving bag workpiece at the time when the remaining sensing elements are about to move beyond the tolerance limit of the desired contour of the bag. In this case, switches controlled by the individual sensing elements may be used to prevent a rejection ofthe bag workpiece in response to properly disposed bag edges.

FIG. 2 shows by way of example a circuit for accomplishing this object. The sensing elements 159 and 160463 consist, e.g., of light barriers having a light source 26 and, on the other side of the path of travel 170 of the workpiece, a receiver 27 succeeded by a photoelectric cell amplifier 28. The path of travel 170 is indicated by a dash-dot line. Each of the sensing elements 164 and 165 consists of a body 171 of grey cast-iron and a radioactive source 172, such as beta-radiating cobalt, which is enclosed in said body. The radioactive radiation 173 is emitted through an opening ofthe body 171, which is shown in section, and penetrates the plane of travel 170 to impinge on a counter tube 174, which delivers counting pulses to an amplifier 175.

Each of the amplifiers 28 and 175 of the sensing elements 159 and 160-165 controls one of switches 176-181 in such a sense that the switch is closed by a dark pulse, which is generated when the bag workpiece or twice the number of plies intervene, and which is open, as shown, when the radiation path is free or contains the normal number of plies. A switch 182 controlled by the sensing element 168 is connected in series with the switches 176-181 and is normally closed when the radiation path is open, whereas the switch is opened by a dark pulse which is produced when a bag workpiece enters the radiation path. As long as the switch 182 is closed, each of switches 176-181 closes the energizing circuit of a relay 57. The opening of switch 182 interrupts the energizing circuit of relay 57. As soon as the leading edge of the bag has covered the photoelectric'cell 168, the actions of satisfactory bag edges on the sensing elements 159 and 160-165 will be ineffective.

For checking the trailing inclined edges of the end closures, elements for sensing said edges must be provided and an additional sensing element must be provided at the intermediate portion of the trailing edge ofthe bag. In this case. the energizing circuit of relay 57 is closed by the element which senses the exiting trailing edge of the bag at the time when the elements for sensing the inclined edges of the bag leave the tolerance range for said inclined edges, whereas a defective inclined bag edge will produce a dark pulse, which causes the corresponding switch also to close the energizing circuit. The tolerance limits can be adjusted by a change of the relation between the sensing elements parallel to the direction of travel.

Because the switches 176-181 are connected in parallel in the energizing circuit of relay 57, the latter will be energized when any of said switches and the switch 182 are closed. The relay 57 has a normally open contact 58, which is disposed in the energizing circuit of a solenoid 60. This circuit includes also a release switch 53, which is closed for a short time once during each working cycle by a camwheel 67, which rotates in synchronism with the cycles of operation of the bag-making machine. The cam 67 acts also on a bell-crank lever 69, which at the same time at which the release switch 53 is closed moves the deflector 25 (FIG. 1) to its position of rest. The means for effecting this movement of the deflector are not shown because they are not a subject matter of the invention. In its position of rest, the deflector is held by the locking lever 61 against the action of the spring 71 on the bell-crank lever 69 during the remainder of the cycle. The solenoid 60 disengages the locking lever 61 at the same time at which the release switch 53 is closed, provided that the relay 57 is energized. When the camwheel 67 has continued its rotation, the tension spring 71 causes a pivotal movement of the deflector to its rejecting position so that the defective bag which has been detected is rejected. This bag has caused an energization of the relay 57 by means of a sensing element and a switch. 1n the time between the brief closing of one of switches 176-181 and the closing of the release switch 53, the relay 57 is held by a self-holding contact 59. The holding circuit includes a switch 63, which is opened between successive cycles by the camwheel 64, which rotates also in synchronism with the cycles ofthe bag-making machine. The opening of said switch 63 interrupts the holding circuit before a new bag enters the checking device.

To detect an error which results in an absence of bag material within the desired contour of the bag, e.g., at an inwardly upset inclined edge of the bag, sensing elements and 186 are provided, which are diagrammatically shown as light barriers in FIG. 6 and are normally covered by the bag, as is indicated by hatching. A bright pulse indicating an absence of bag material closes one of the switches which are associated with the sensing elements 185 and 186, respectively. A second switch is connected in series with the switch that is controlled by the sensing element 185. Said second switch is controlled by a diagrammatically indicated sensing element 187 and is closed by a dark pulse received by the photoelectric cell 187 when the bag workpiece 188 continues to move in the direction of the arrow 189 because the intermediate portion 190 of the leading edge 191 of said bag workpiece is always in the desired position. The sensing element 187 is so related to the sensing element 185 that the switch controlled by the sensing element 187 will not be closed until the sensing element 185 is beyond the inner tolerance limit for the inclined bag edge 192. This is indicated in the drawing in that the photoelectric cell 187 is unhatched also outside the leading edge of the bag to indicate that the cell is illuminated in this region whereas the photoelectric cell 185 is behind the inclined bag edge 192. This showing does not necessarily represent the exact relation of the two cells. Adjacent to the trailing edges of the bag, the relations are inverted inasmuch as the photoelectric cell 186 is just about to leave the error range so that the circuit which is closed by its switch in response to a light pulse must be interrupted before. This has just been effected by the series-connected switch, which has been opened by the light barrier 193 in response to a light pulse.

For a comparison, the sensing elements are shown which serve to detect defective parts disposed outside the contour of the bag. The sensing elements 194 and 195 are, e.g., light barriers, which at the instant which is illustrated are normally illuminated and for this reason are shown unhatched. When bag corners extending, e.g., to the dash-dot lines 196 and 197,

produce a dark pulse, the photoelectric cells close the switch which is associated with them. As the photoelectric cell 194 is already approaching the tolerance range of the desired inclined bag edge portion 192 indicated by a solid line, a switch which is associated with the photoelectric cell 198 has been opened because the bag has produced a dark pulse. The photoelectric cell 195 is about to leave the tolerance range of the desired trailing inclined edge 199 of the bag and is soon rendered effective by a switch which is associated with a photoelectric cell 200 and which is closed by a light pulse when the photocell 200 leaves the workpiece as the circuit which is closed in response to a dark pulse by the switch associated with the photoelectric cell 195 is also closed by the switch associated with the photoelectric cell 200.

It is desired to prevent an energization of the relay 57 by the sensing elements 185 and 186 which close the respective switch in response to a light pulse between two bag workpieces. Such energization might result because the photoelectric cell 187 for sensing the leading edge of the bag still holds its associated switch closed while the photoelectric cell 185 leaves the trailing inclined edge 199 of the bag and the photoelectric cell 193 which senses the trailing edge of the bag has already closed its associated switch in response to the next bag while the photoelectric cell 186 has not yet been covered by the leading inclined edge portion of the next bag. To this end, the invention provides an additional switch, which is in series with the above-mentioned switches and operated by a timing disc to open the circuit during these intervals.

The photoelectric cells which cooperate with a photoelectric cell serving to sense the leading or trailing edge of the bag, on the one hand, and the switches controlled by the former photoelectric cells, on the other hand, are included in respective parallel circuits for energizing the relay 57 so that each circuit controls the relay 57 independently of the other.

FIG. 3 shows a bag end which has not been pulled open but has remained flat in the pulling-open station and has only been backfolded in accordance with an outer lateral end flap in the station for reversely folding the lateral end flaps. FIG. 7 shows a bag, in which one end 205 has not been pulled open and has been backfolded as a whole onto the body ofthe bag about the center fold line 206 ofthe end closure and has been folded out about the fold line 207 as far as to the line 208 in the station for reversely folding the lateral end flaps and provided with an end patch 210. FIG. 7 shows also that the diagonal scoring and the running against a folding tool of the like have caused the preceding corner 211 to be backfolded on top ofthe reversely folded end portion of the tube section. This results in an even larger accumulation of material in this corner than in the remaining area ofthe inner lateral end flap. To enable a detection and rejection of the bags having the defects described above, the checking device comprises additionally a mechanical sensing element, which responds to the differential level that is due to the absence of the outer lateral end flap.

A two-armed lever 216, 217 is pivoted on a pivot 215, which is carried by the machine frame. The lever arm 216 carries at its free end a bearing 218, in which the pin 219 ofa T- shaped member 220, 221 is rotatably mounted. The flange 221 of the Tcarries at each end a pin 222, on which a sensing roller 223 or 224 is rotatably mounted and held captive. A tension spring 225 (FIG. 8) acts on the free end of the lever arm 217 by means ofa spring-retaining pin 226 (FIG. 9). The other end of said spring is secured to a fixed point. The spring 225 urges the two-armed lever 216, 217 in the clockwise sense against a set screw 227 so that the rollers 223, 224 give way against the force of spring 225 and effect a pivotal movement 'of the double lever 216, 217. One such sensing element is disposed over each of the two bag ends 205 and 228 (FIG. 7) in such a manner that the two rollers move symmetrically with respect to the end closure center line. By causing a rotation of the pin 219 in the bearing 218, the rollers adjust themselves to the different thicknesses of the workpiece. Even a properly folded crossed end closure (FIG. 10) will cause a slight inclination of the T-member 220, 221 because the inner half 229 of the crossed end closure lies on the bag body 230 whereas the outer half 231 of the crossed end closure does not. The above-described improper folding of the bag end 205 (FIG. 7), however, results in a great inclination (FIG. 9) because the outer half of the end closure is absent or represented only by the end patch. In response to this great inclination, the means described hereinbefore close an electric contact.

The pin 219 has an extension 235, which protrudes from the bearing 218. A lever 236 is secured to that extension and acts on the actuating pin 237 of a limit switch 238, which is secured to a rod-shaped holder 239. The latter is screw-connected to the bearing member 218. In position of rest, when the two rollers 223 and 224 are not engaged by a workpiece, an adjusting screw 240 carried by the lever 236 engages the holder 239 under the action of a tension spring 241, which is just sufficient for this action. In this condition, the actuating pin 237 is fully depressed and has thus fully opened the normally closed contact. When the rollers are engaged by a normal bag end closure, as is shown in FIG. 10, the lever 236 has a slight inclination, which is not sufficient to release the actuating pin so as to close the contacts. Only a bag end which is defective as shown in FIGS. 7 and 9 causes the lever 236 to be sufficiently inclined for a release of the actuating pin 237 to close the associated contacts. This may initiate an operation of the deflector 25, e.g., by an energization of the relay 57, so that this bag is rejected.

To convert a bag-making machine provided with the embodiment which has just been described to the manufacture of bags having a different size, numerous sensing elements must be repositioned. Even if the sensing of the rear inclined edges of the infolded corner portions and the checking of the inclination by sensing elements in the path of travel of the outer ends of the leading edges of the bag were omitted, a change in size would still require a repositioning of eight elements for sensing the end closures and one element for sensing the leading edge of the bag relative to each other to suit the new size. In the arrangement shown in FIG. I, this would be the sensing elements I3, l5, I7, 19, 159, 160, 164, 165, and 168. This requires a prolonged setting-up time, which would obstruct the production, particularly by the long standstill times ofthe machine.

According to a further proposal of the invention, these difficulties are avoided in that the sensing elements associated with each half of an end closure are carried by a common holder and the two holders for each end closure are relatively adjustable transversely to the direction of travel of the workpiece. The adjustment of the holders may be read from a scale which is calibrated in end closure width dimensions. It is also suitable if the two holders for each end closure are adjustable by equal amounts by means of a right-hand and left-hand screw provided with a handwheel. The relative movement of the two holders serves for an adjustment to a different end closure width. The adjustment to different bag lengths is effected simultaneously with the overall adjustment of the two halves of the machine to the new lengths because each holder is carried by the associated half of the machine. In this case the sensing element disposed in the middle of the leading edge of the bag, in FIG. I the sensing element 168, must be adjusted only by one half of the difference between the end closure widths in or opposite to the direction of travel of the workpiece, which is the direction 8 in FIG. 1, in the case of a change in size. This adjustment can also be facilitated by a scale which is calibrated in end closure width dimensions.

To enable this simple adjustment of the sensing element which is disposed at the center of the leading edge of the bag, it is assumed that the sensing elements for sensing the inclined edges of the infolded corner portions (elements 159, I60, 164, in FIG. 1 may have the same spacing from the end closure corners with all sizes of end closures. The distance from the leading edge of the bag to the corners of the bag and consequently to the elements for sensing the inclined edges of the infolded corner portions in the direction 8 in FIG. I changes by one half of the difference between the widths of the end closures because the edges are inclined at an angle of 45.

According to a further proposal, the two screws for adjusting the holders for each end closure may be operatively connected so that the screw only on one side of the machine may be adjusted by means of a handwheel or the like and the adjusting screw for the other side of the machine performs the same adjustment owing to the the operative connection.

The provision of a common holder for the sensing elements associated with each half of an end closure and the arrangement of these two common holders so that they are relatively adjustable transversely to the direction of travel of the workpiece may be advantageous even if such holders carry only the elements for sensing the inner edges of the end closures.

lclaim:

I. An apparatus for inspecting folded bag bottoms and for rejecting defective bags, the apparatus comprising: a deflector disposed between the bottom-laying and delivery stations of a bag-making machine, the deflector being controllable by bottom-checking means which serves to deflect defective bags from their path of conveyance, said bottom-checking means comprising mechanical sensing means for checking the number of plies of the outer bottom halves of the bags and switching means cooperating with said sensing means and said deflector to react if the number of plies is improper.

2. The apparatus defined in Claim 1, wherein said mechanical sensing means comprises a pair of rollers each provided at an end of a double-armed lever, said lever being pivotable against spring force about an axis disposed substantially over the path of travel of the center line of the bag bottom and parallel to the latter and adapted to actuate said switching means.

3. The apparatus of Claim 2, wherein said mechanical sensing means are pivotally mounted to move against spring force, about axes transverse to the direction of travel of the bags.

4. A bag-making machine which comprises a deflector, which is disposed between the end closure-laying and delivery stations and which is controlled by end closure-checking devices to reject defective bags from the path of conveyance, characterized in that the end closure-checking devices comprise means for checking crossed end closures as to the presence of the inclined edges of the infolded corner portions and the agreement of the actual position of such edges with their desired position, characterized in that the sensing elements associated with each half of an end closure are carried by a common holder and the two holders for each end closure are relatively adjustable transversely to the direction of travel of the workpiece.

5. A bag-making machine according to Claim 4, characterized in that the adjustment of the holders is readable from a scale which is calibrated in end closure width dimensions.

6. A bag-making machine according to Claim 4, characterized in that the two holders for each end closure are adjustable by equal amounts by means of a right-hand and lefthand screw provided with a handwheel.

7. A bag-making machine according to Claim 4, characterized in that the sensing element disposed in the middle of the leading edge of the bag is adjustable in the direction of travel of the workpiece.

8. A bag-making machine according to Claim 7, characterized in that the setting of the feeler which is disposed in the middle of the leading edge of the bag is readable from a scale which is calibrated in end closure width dimensions.

9. A bag-making machine according to Claim 6, characterized in that the two adjusting screws for adjusting the holders associated with each end closure are operatively connected to each other. 

